Source: http://monsterhunter.wikia.com/wiki/Ceadeus

Ceadeus is a Elder_Dragon introduced in Monster Hunter 3.

Ceadeus' right horn is much thicker than its left and halfway envelops its right eye. It can be broken off and carved twice. It's face closely resembles that of a Dunkleosteus, a species of large, extinct, carnivorous fish that was covered in large bony plates. Its neck resembles Lagiacrus' hood-like structure, but with a large fur coat underneath. This 'beard' can be broken and its hood and tail scarred. The quest can be taken multiple times, with Ceadeus unable to recover its health between quests. Eventually, once enough damage has been dealt, it will be killed.

Ceadeus is the only offline monster players fight (in Monster Hunter Tri) that is able to inflict Dragonblight, a status effect that decreases affinity for a fixed amount of time before disappearing. Other monsters capable of inflicting this ailment include Deviljho and Alatreon, along with Stygian_Zinogre in Monster Hunter 3 Ultimate, and it is unique to monsters with the dragon element.

The Ceadeus is known to be a rather peaceful creature until provoked. They do not bother humankind unless they feel threatened.

It resides in a series of underwater canyons and ruins deep below Moga Island, but is unable to travel onto land.